Preheat the oven to 350°. In a bowl, mix the grits, flour, salt, baking soda and cayenne. Rub in the butter until the mixture resembles coarse meal. Stir in the Parmesan and make a well in the center. Add the buttermilk and stir to form a stiff dough. Knead on a lightly floured surface until smooth. Wrap in plastic and let stand for 15 minutes.
Cut the dough into quarters. Set one quarter on a lightly floured surface; cover the remaining pieces with plastic. Roll out the dough 1/16 inch thick. Using a 2-inch round biscuit cutter or a glass, cut out rounds of dough and arrange them on a nonstick baking sheet. Bake for 12 to 14 minutes, or until golden and crisp. Transfer to a rack and let cool. Repeat with the remaining dough.
Make Ahead: The crackers can be stored in an airtight container for up to 2 weeks.
Notes: FIVE CRACKERS: Calories 98 kcal, Protein 3 gm, Carbohydrate 9 gm, Cholesterol 5 mg, Total Fat 5 gm, Saturated Fat 4 gm